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Message-Id: <200910162142.50618.arnd@arndb.de> Date: Fri, 16 Oct 2009 21:42:50 +0200 From: Arnd Bergmann <arndbergmann@...glemail.com> To: Alan Cox <alan@...rguk.ukuu.org.uk> Cc: Arnd Bergmann <arndbergmann@...glemail.com>, Thomas Gleixner <tglx@...utronix.de>, LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>, Frederic Weisbecker <fweisbec@...il.com>, Jeff Dike <jdike@...toit.com> Subject: Re: [patch 6/7] um: Convert mmapper to unlocked_ioctl On Thursday 15 October 2009, Alan Cox wrote: > On Thu, 15 Oct 2009 15:00:34 +0200 > Arnd Bergmann <arndbergmann@...glemail.com> wrote: > > > However, returning -ENOIOCTLCMD from an *unlocked_ioctl* function > > automatically gets turned into -EINVAL. It does this to allow > > the same functions to be used for unlocked_ioctl and compat_ioctl. > > In effect, this patch is functionally identical to removing the > > ioctl function, which I think is what should be done here. > > That is wrong. > > SuS requires an unknown ioctl code returns -ENOTTY. If the code is > currently remapping it to EINVAL then it wants fixing. Right, I forgot about the EINVAL/ENOTTY difference. The code currently returns -ENOIOCTLCMD, which is worse. Thomas' patch makes it return -EINVAL, which as you said is still wrong. Removing the ioctl function will do the right thing and return -ENOTTY, so that should be done here in um/mmapper, with an appropriate changelog. For the common code in fs/ioctl.c, I think the current behaviour is correct. It returns -EINVAL if the driver returns -ENOIOCTLCMD, iow "the request [...] argument is not valid for this device", as specified by http://www.opengroup.org/onlinepubs/009695399/functions/ioctl.html. Drivers returning ENOIOCTLCMD for every request are broken and should be changed to have no ioctl function. Arnd <>< -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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